More than 5.4 million Americans and 35 million people worldwide have Alzheimer's disease, the most common form of dementia. Currently, the only definitive way to diagnose Alzheimer's disease is by direct examination of brain tissue after a patient dies. Doctors use brain imaging, evaluation of behavior, psychiatric tests, and other means to diagnose the disease in the patients suspected of having Alzheimer's disease, but none are highly accurate, and many are costly or not practical.
Therefore, there is a need in the art for biomarkers and methods for diagnosing Alzheimer's disease and other neurodegenerative disorders. Additionally, there is a need in the art for compositions for detecting the biomarkers as well as compositions and methods useful for treating Alzheimer's disease and other neurodegenerative disorders. The present invention meets this need by providing accurate, noninvasive methods for diagnosing Alzheimer's disease and other neurodegenerative disorders. The present invention further provides novel methods, assays, kits, and compositions for diagnosing, prognosing, predicting, and treating Alzheimer's disease and other neurodegenerative disorders.